Patient positioning system for radiotherapy

ABSTRACT

The invention concerns a patient positioning system for radiotherapy, comprising a device for positioning a patient within the framework of treatment planning, using image detection and/or carrying out radiation treatment, comprising a patient bed ( 3, 42, 50 ) on which a patient is positioned, wherein means are provided by which the same bed ( 3, 42, 50 ) may be arranged both on a planning couch ( 8 ) for image detection within the framework of treatment planning as well as on a radiotherapy table ( 1, 44 ), and by providing a reference means ( 54 ) on the patient bed by which the position of the immobilised patient or of a marked radiation target is determined with respect to the patient bed ( 3, 42, 50 ). Within this framework, a corresponding method is also provided, as well as an adjusting means for the transport and the bed.

This application is a continuation of U.S. patent application Ser. No.09/949,294 filed on Sep. 7, 2001, now U.S. Pat. No. 6,865,411 which ishereby incorporated herein by reference in its entirety.

The present invention concerns a patient positioning system forradiotherapy, or for radiation therapy or radiosurgery. In principle,the procedure within the framework of such radiation treatments is thatradiation planning is undertaken first of all, wherein image recordingsare taken of the patient or of the area of the patient around theradiation target, for example computer tomography recordings. Thetreatment target is registered via known marking systems. In accordancewith the present standard, the patient is then taken off the bed at theimage-generating device, and goes independently to the radiotherapy roomin order to lie down there on another bed at the radiotherapy apparatus.Here, one attempts via a tracking system to determine the currentposition of the radiation target, using the position of the markingsarranged on the patient, and/or to position the patient by means of atracking system, such that the treatment target lies in the isocentre ofthe radiotherapy apparatus. Typically, the image data for planning arenot recorded on the same day as treatment takes place.

This approach involves a great disadvantage, alone because of themovement of the patient between the two patient beds. Markings which aremostly arranged on the patient's skin shift during this relocation, inrelation to each other and to the radiation target point. Positioningfor radiation exposure on the radiotherapy apparatus, and therefore theradiotherapy itself, thus becomes imprecise, which possibly brings thesuccess of the treatment at least partly into question.

A similar problem arises if the position of the radiation target isdependent on the respective breathing state of the patient. If thepatient's planning data set, for example, was recorded while the patientwas holding his breath, this data set represents the patient and theposition of the target volume at a specific lung filling. In order to beable to transfer these data to the state of the patient at the time ofradiation exposure, the lung filling would have to exactly correspond atthe two points in time. If the patient is able to breathe freely duringradiation exposure, this is at most the case at two points in time perbreath. Moreover, the breathing drift, being a shift of the underlyinglung volume over medium periods of time, will present a problem.

Here too, the problem arises of the transferability of the 3D planningdata set to the state of the patient at the time of radiation exposure.

Previous approaches for solving the above latter-mentioned problem havemade use of the fact that a patient's breathing may be tracked byobserving the outer contour of the thorax and abdomen. If markings arearranged on the patient's skin, these can then be correlated with theposition of inner target volumes. However, if the patient is relocatedafter the image-generating examination (for example CT, MR, SPECT, PET)has been carried out—wherein the patient typically has to get up, walkto the radiotherapy room, and there lie down on another bed—then thesebaceous layers of the patient again slip here, and therefore also themarkings arranged on them. This in turn results on the one hand in aninaccurate position of the patient co-ordinate system, as well as to aclear distortion of a possibly previously determined correlation betweenthe breath-dependent position of the target volume and the externalmarkings. For this reason, in accordance with a known approach tosolving this problem, correlation is carried out directly, on theradiotherapy apparatus table. This in turn is disadvantageous, becausethe image-generating methods usable are either of a lower qualitycompared to the devices described above, or require a high level ofinvestment, since either the therapy device or the image-generatingdevice may be used, but not both at the same time.

It is the object of the invention to solve the problems cited above.This is solved in accordance with the invention by a device as set forthin the enclosed claim 1 and is based on the one hand on using the samepatient bed for positioning the patient on the image-generating device,and for radiation exposure. In other words, the patient can remain lyingon one bed, and is taken together with the bed from the planning systemto the radiotherapy apparatus. In this way alone, the shifts in animmobilised patient resulting from relocation are considerably reduced.Furthermore, the advantageous accuracy of the system in accordance withthe invention is also based on providing a reference means on thetransportable patient bed with which the position of the immobilisedpatient, or of one or more marked reference points on the surface of thepatient's body, may be determined with respect to a point fixed on thepatient bed. Using this reference means provides an additional fixedreference point near the target volume defined by the markings on thepatient and which is very helpful as a fixed positioning quantity, andin particular when a radiation target volume alters its position withthe patient's breathing. In previous methods, in which only the positionof the patient markings has been used for breath-dependent radiationexposure, an external reference has been lacking which for example wouldrecognise a drift, i.e. a shift in the underlying lung volume. Inaddition to the unstable relationship between the patient makers and thetarget volume mentioned above, this could lead to inaccuracies inradiation exposure. Through lack of an external reference, which allowsan absolute lung filling co-efficient to be determined, it hasaccordingly not been possible so far during treatment to allocatetriggered image recordings to a defined breathing state.

The fact that such a reference means is now provided on the patient bedin accordance with the invention makes it possible to produce “absolute”patient marker positions, so to speak, with respect to the referencemeans fixed to the bed. In this way, any shifts in the patient markingsbetween one another, but also with respect to the patient bed system,may be identified and corrected, or considered as to whether these havearisen because the patient has moved, or from breathing movement. Imagerecordings triggered relative to an absolute lung filling value enableradiation exposure triggered in the course of the treatment withsubstantially greater precision, i.e. radiation exposure only takesplace when the target volume is located at a specified place. In thissense, the present invention helps to avoid positioning errors and toaccurately take into account the shifting of organs due to breathing andtherefore also allows much more precise and effective radiation exposurethan is currently possible in accordance with the prior art.

In a preferred embodiment of the device in accordance with theinvention, the device—as already indicated above—comprises a trackingsystem which can detect both the positions of markings arranged on thepatient as well as those of the reference means, in particular of areference star fitted with an arrangement of markers, on the bed. Itshould also be stated in particular in this respect that such areference star, which may for example comprise an arrangement of threeinfrared reflecting markers, can be observed together with the patientmarkings during the tomographic imaging (CT) inside the tomography room,so that triggered recordings are possible which then later allowtriggered radiation exposure when the patient markers and the markers onthe reference star are in a defined relationship, namely +/− a permittedtolerance range around their position (relative to the reference means),during the tomographic imaging. Also conceivable here, as an extension,is taking various planning image recording sets of the same area for anumber of defined states (distance ratios) of patient markers andreference markers on the bed, and thus analysing the movement of thetarget point. The “beam-on range”, i.e. the period during which thetreatment beam is switched on in the treatment, can then be individuallydefined for the predetermined marker relationship above. Thus, acomplete set of starting points is already available during imagerecording, i.e. during planning.

In order to be able to implement the invented system, however, it ispossibly disadvantageous to only use conventional devices correspondingto the prior art. For this reason, the present invention comprises a newtype of patient bed, whose use is itself only possible in conjunctionwith a new type of angle-adjusting device for positioning the patientduring radiation exposure.

The device in accordance with the invention advantageously comprises oneor more of the following immobilisation means for immobilising thepatient on the patient bed:

-   -   vacuum foils with corresponding vacuum pumps    -   elastic bands or foils stretched over the patient    -   vacuum cushions specially fitted to the patient's form    -   thermoplastic body masks specially fitted to the patient's form    -   form cushions or form blocks fitted to the patient's form

A device in accordance with the invention for positioning the patientwithin the framework of treatment planning using image detection and/orperforming a radiotherapy treatment, comprising a patient bed on whichthe patient is positioned, in particular a device as described above,can include an adjusting device with which the patient bed can berotated about at least two axes, and which is arranged between thepatient bed and a supporting device for the patient bed, in particular aplanning couch or a treatment table. This tackles the problem that inmost cases of image detection and patient irradiation, the angle ofrotation about the longitudinal axis of the body and the horizontallateral axis are not identical in this respect. Therefore, the pathwhich the beam takes to reach the treatment target is in most cases notidentical with the path determined during the planning for radiationexposure treatment as the optimum treatment. Stereotactic radiosurgerypre-supposes the possibility of being able to irradiate a specifiedtarget area within the patient's body from a specified direction.However, due to the limited rigidity of the tables of linearaccelerators and similar radiosurgical and radiotherapeutic systems, itis often the case that the part of the body to be treated, or the entirepatient, experiences an angular rotation after having been fixed on thetreatment unit, which accordingly has to be corrected. In order to carryout this correction, systems are used in the prior art, in which thehead of the patient can be turned laterally or longitudinally within aspecified angular range.

Such a patient table system with an adjusting device in accordance withthe prior art is shown schematically in FIG. 10. The adjusting device Cis fixed to the treatment bed B of the therapy device and receives thehead by means of a mask or screw ring system D. In order to achieve thenecessary rigidity, these adjusting mechanisms are heavy and relativelylarge. In order to take the forces and momenta out of their own weightand the weight of the patient's head and to be able to transfer these tothe treatment bed, it is necessary to provide relatively solid and heavyabsorbing devices on the patient table. However, these absorbing devicesare problematic, inasmuch as they cannot be as radioparent as a simple,continuous (carbon) bed. An additional problem is the size of thedevices, which significantly increases the risk of collision between thebed and the part of the radiation exposure unit being moved and makesthe transport of the bed considerably more difficult. Moreover, theangular adjustment cannot be used for extra-cranial radiation exposure,and it is precisely this deficiency which is a substantial disadvantagedue to the recently achieved advancements in the field of extra-cranialradiotherapy.

The device described above solves this problem through by arranging theadjusting device between the patient bed and the supporting unit for thepatient bed, i.e. for example the CT couch or the treatment table. Inthis way, the angular adjustment can be made for all parts of thepatient's body, and the adjusting device is no longer in the way duringrecording, and is no longer a disturbance to the radiotherapy apparatus.

Combination with a detection system (tracking system) is possible.

The adjusting device can enable the patient bed to turn independentlyabout at least one axis laterally and one axis longitudinally to thebed. It preferably consists of a base plate and a cover plate which aremovably linked together via a three-point or four-point bearing. It ispossible in this connection to design the adjusting device in such a waythat it comprises at least two supports which are constructed as heightadjustable, pneumatic, hydraulic, piezoelectric or electromechanicalsupports, adjustable directly or by means of a lever system.

The adjusting device preferably comprises a front, head-end support anda rear, foot-end support, wherein at least one of the supports isconstructed as a ball joint or as a universal joint. The front or rearsupport can in this respect comprise toggle levers with ball joints onboth sides.

In an arrangement of the device in accordance with the invention, thebearing of the cover plate on the base plate includes a shaft-groovejoint with two translatory and two rotatory degrees of freedom, whichprevents the cover plate from shifting laterally with respect to thebase plate. On the one hand, the device can comprise adjusting meanswhich cause the bed to rotate about its longitudinal axis bycounter-adjusting two head-end or foot-end supports, on the other handthe adjusting means can cause the bed to rotate about its lateral axisby synchronously adjusting one or two head-end or foot-end supports.Both, of course, can be realised. The adjusting means can similarlycause the bed to rotate about its lateral axis by simultaneouslyadjusting at least one head-end and at least one foot-end support.

Attention must be paid to the adjusting speed, especially when usingtoggle levers. In one embodiment, the device therefore comprisesadjusting means which cause the bed to rotate about its lateral axis bypurposefully setting the adjusting speed of at least one head-end and atleast one foot-end support, wherein the position of the apparent axis ofrotation may be placed in a desired position. The device can furthercomprise adjusting means which cause the bed to rotate about itslongitudinal axis by purposefully setting the adjusting speed of atleast two supports, whereby the position of the apparent axis ofrotation can be placed in a desired position.

Furthermore, a device is provided in accordance with the invention forpositioning the patient within the framework of treatment planning usingimage detection and/or of carrying out radiation planning, using apatient bed on which a patient is positioned, in particular a device asdescribed above, said device including a transport device, in particulara transport trolley for transporting the bed with the patient lying onit. Such a transport device can optimally supplement the advantageousembodiments of patient positioning as already described above, wherebyin a preferred arrangement two latching mechanisms are provided forconnecting the patient bed and transport trolley, for attaching thepatient bed to a table of a treatment system and to a couch of animaging planning system. The bed may on the one hand be attached to anddetached from the table of a radiotherapy apparatus or the couch of theplanning system by adjusting the height of the table or couch; on theother hand, there is also the possibility of realising this by adjustingthe height of the transport device.

The invention further provides a method of treatment planning usingimage detection and/or carrying out a radiation treatment. In thismethod, the patient is positioned on a patient bed, the same patient bedbeing used both on a planning couch for image detection within theframework of treatment planning, and also on a radiotherapy table, andthe position of the immobilised patient or of a marked radiation targetis determined with respect to the patient bed via a reference meanswhich is securely provided on the patient bed. Of course, the method inaccordance with the invention also has the advantages over the prior artby way of the device, as already described previously.

In particular, in a method in accordance with the present invention, thebed on which the patient is lying is removed from the planning couch,transported to the radiotherapy apparatus and there re-attached. Atracking system on the imaging device may detect and/or be adjusted toboth the position of markings attached to the patient as well as thereference markings on the bed, and can be adjusted in accordance withthese. The patient is preferably secured on the bed in such a way thathe can neither shift relative to the bed, nor change the position of theparts of his body with respect to one another.

If the method in accordance with the invention is used forbreath-synchronised radiation exposure, the secured patient is fittedwith external markings, wherein it is verified by way of the position ofthese markings relative to the reference means that the patient held hisbreath while the planning data were recorded.

In accordance with a further arrangement of the method in accordancewith the invention, the position of patient markings relative to thereference means is determined, and where it corresponds with pre-setfigures including tolerances, image recording is started or stopped whenthe patient holds his breath, starts breathing again, has reached aspecified lung filling or exceeds a specified lung filling in a givenbreath phase (for example, during breathing in or breathing out).Furthermore, it is possible to irradiate the patient only at those timesat which the position of patient markings relative to the position ofthe reference means securely attached to the bed lies within a definedtolerance range about the relative position which obtains while aplanning data set is being recorded (triggered radiation exposure).

The invention will now be described in more detail by way of preferredembodiments. The enclosed drawings show:

FIG. 1 a patient table-patient bed system with an adjusting device inaccordance with the present invention, in an oblique view in an imagedetection system, and in a side view as it is being used for radiationexposure;

FIG. 2 an adjusting device in accordance with the invention, in an upperand lateral sectional view;

FIG. 3 a rear bearing of the adjusting device, in a lateral, enlargedview;

FIG. 4 a frontal view of an embodiment variant of the adjusting device,comprising two toggle levers and an additional guide joint;

FIG. 5 Sectional side views illustrating a way for the toggle levers ofthe adjusting device to adjust;

FIG. 6 a frontal view of the adjusting device showing thecounter-adjustment of two toggle levers;

FIG. 7 an embodiment variant of a self-supporting carbon bed on thecouch of a conventional linear accelerator;

FIG. 8 an embodiment of a transport system for a patient bed;

FIG. 9 an embodiment of a mechanism for latching and releasing the bedon the adjusting device or directly on the couch; and

FIG. 10 a schematic diagram of a patient table-patient bed system withan adjusting device in accordance with the prior art.

FIG. 1 shows a patient table-patient bed system with an adjusting devicein accordance with the present invention, in an oblique view in an imagedetection system (planning), and in a side view as it is being used, forexample, in radiation therapy under a LINAC (LInear ACcelerator). Theupper oblique view (in the planning step) shows: a planning systemconsisting of a patient couch 8 and an imaging device 2, for example aCT device; and a schematically illustrated latching mechanism 7, withwhich a patient bed 3 can be fixed to the couch 8. In the lower diagram,the bed 3 for radiation exposure is placed on a patient table 1, and anadjusting device 6 is inserted between a further latching mechanism 4 onthe patient table 1 and the patient bed 3.

Instead of the hitherto usual arrangement sequence of the connectingstructure: table (A)—bed (B)—adjusting mechanism (C) (see FIG. 10), theconnecting structure: table (1, 8)—adjusting mechanism (6)—bed (3) isimplemented. Accordingly, the angular correction can also be used fortreatment outside of the head area. The second advantage of thisprocedure is that the bed 3 on which the patient is lying can beconstructed throughout from highly radioparent carbon material, even inthe neck area; reinforcements, support points and screw points on thepatient bed 3 are dropped completely.

Since the system portrayed here is also intended for rigging alreadyexisting radiotherapy systems, it is particularly important that theadjusting device 6 can be integrated into a considerably restrictedbuilding space. This requirement, however, cannot be realised withconventional systems having two axes of rotation. The system inventedtherefore uses a special suspension in the adjusting device, a preferredembodiment being described in the following by way of FIG. 2.

FIG. 2 shows an adjusting device 6 in accordance with the invention, inan upper and lateral sectional view. It comprises a base plate 10 and acover plate 12. The connection between the base plate 10 on the table ofthe treatment device and the cover plate 12 on which the (carbon) bed 3is fixed, is realised by a three-point bearing 15, 16, 17, supplementedby an additional lateral guide joint 14. The rear bearing 15(approximately at the level of the patient's feet) is a ball jointbearing with three rotatory and no translatory degrees of freedom. Thisis again shown enlarged in FIG. 3. Alternatively, this bearing can bedesigned as a universal joint.

The front two supports 16, 17 consist of toggle levers which are fixedto the base plate 10 and cover plate 12 respectively with ball joints18, 19, 20, 21, which can best be seen in the frontal view in FIG. 4.

The side guide joint 14 is located near the centre line between the twotoggle levers, and comprises two rotatory and two translatory degrees offreedom. A preferred embodiment of this joint is a shaft 22 which isguided in a slot 23. Alternatively, this joint can also be omitted if abearing with only two rotatory degrees of freedom is selected on theother side of the mechanism.

FIG. 5 shows sectional side views which illustrate a way for the togglelevers 16, 17 of the adjusting device 6 to adjust, and FIG. 6 shows afrontal view of the adjusting device 6 showing counter-adjustment of twotoggle levers 16, 17. The two toggle levers 16, 17 can be guided byelectrocylinders (30) (each being a spindle-and-nut system), hydrauliccylinders or pneumatic cylinders.

If the two toggle levers 16, 17 are spread in the same direction, thebed 3 can be turned about an axis perpendicularly to the patient; if thetoggle levers 16, 17 are spread in different directions, then rotationabout an axis which is approximately parallel to the longitudinal axisof the patient may be realised.

In order to realise rotation about the main axes (the axis through therear ball joint 15, perpendicular to the symmetry plane of the patient,and the axis parallel to the symmetry plane of the patient), it isnecessary to alter the effective height of the toggle levers 16, 17 withan identical and/or reverse speed. Such a counter-adjustment leads, forexample, to a state such as shown in FIG. 6. Since the toggle levers 16,17 exhibit a path and power transmission which is dependent on thebuckling angle, it is necessary to guide the toggle levers withdifferent amounts of speeds, calculated depending on the buckling angleof the two toggle levers. If this is realised, then it is possible toturn the bed 3 about the longitudinal axis without changing the angleabout the lateral axis or the height of bed 3.

Alternatively, the ball joint 15 can also be designed by a third togglelever with a one-sided ball joint and a simple rotating bearing on theother side of said toggle lever (not shown). In such an embodiment, thethird toggle lever is located in place of the ball joint bearing and islikewise fixed to the base plate and to the cover plate by ball jointbearings. With the aid of said third lever, it is additionally possibleto turn the patient about a virtual lateral axis, whose position can beset by the ratio of the effective speeds of the single toggle lever inrelation to the effective speed of the two toggle levers on the otherside. In this way, it is possible to turn the patient lying on the bedabout a specified point, preferably about the point to be treated. Inthe case of a linear accelerator, this is the isocentre.

FIG. 7 shows a possible embodiment of a patient bed 50 on the adjustingdevice 6. A head support 53 is shown which cannot be turned and cantherefore be realised in very thin and therefore radioparent carbon. Anend plate made of metal may be provided as 55, which can serve to fixthe bed 50 to an adjusting device 52, or which can also be used toconnect foot supports or similar additional devices to the bed 50.Infrared-reflecting markers are arranged on a reference star 54, whichcan be used as reference markings for markers located on the patient. Aframe 56 integrated into the bed is substantially shorter than theactual bed and thereby does not extend into areas which are to beradioparent.

So that the position of the patient on the bed 50 during treatment isthe same as that while the planing data set is being recorded, thepatient is not allowed to move between these points of time. The bed istherefore preferably combined with a patient fixing system. Suitable forthis, among other things, are:

-   -   vacuum foils with corresponding vacuum pumps    -   elastic bands or foils stretched over the patient    -   vacuum cushions specially fitted to the patient's form    -   thermoplastic body masks specially fitted to the patient's form    -   form cushions or form blocks fitted to the patient's form

The star 54 with the reference markers is securely connected to the bed50. The patient's breathing changes the distance between the referencemarkers and possible markers on the patient's thorax. This distance issuitable for describing the patient's breathing. The correlation betweenthis distance value and the position of internal organs of the patientis maintained when the bed 50 is transported, since both the referencemarkers and the patient are securely connected to the bed. A trackingsystem (not shown) at the planning location (for example CT) and at thetreatment location (LINAC) assists, for example, breath-controlledplanning and radiation exposure (triggered CT recordings and triggeredradiation exposure), wherein this is only possible because theabove-mentioned correlation is maintained. In this respect, a certaintolerance range is also to be maintained. Similarly, the bed 50 isautomatically positioned at the LINAC (computer-assisted via thetracking system and the markers on the star 54 on the bed) only when thedefined relationship has been reached. It is conceivable as an extensionthat various CT sets of the same area are recorded at several definedpatient-fix-marker states, in order to provide several “starting points”as early as the CT. A physician can then analyse the movement of thetarget point, and a “beam-on range” during radiation exposure(permissible patient-fix-marker relationship for “beam-on”) can beindividually defined. In the case of CT planning, this method is tostand only as one example of an imaging method. In principle, the use ofother methods is possible, for example MR, SPECT, PET.

In order to be able to make good use of the advantages of atransportable patient bed, it is advantageous to have a device whichallows the bed, together with the patient, to be transported from theimaging system to the treatment device. FIG. 8 shows an embodiment of atransport system for a patient bed 42. A transport trolley 41 holds thebed 42 in a broadly horizontal position. When the trolley 41 is movedover the table 44 of the treatment device or of the imaging system, thebed 42 can then be delivered onto the adjusting device 43. The trolley41 is fitted with side rollers 45 on the inner side of the two lowersupports, such that the trolley 41 centres itself automatically withrespect to the table 44. The trolley 41 is fitted with side rollers 48at the end facing away from the bed, so that it is possible to pushdoors open with the trolley 41.

FIG. 9 shows a possible embodiment of the mechanism for latching andreleasing the bed on the adjusting device or directly on the couch. Theessential advantage of this mechanism lies in the fact that nosignificant physical force need be applied, as the force is applied bythe table. Both the tables from linear accelerators as well as thosefrom MR and CT systems allow the height of the table to be adjusted. Anend plate 70 (reference numeral 46 in FIG. 8), securely connected to thepatient bed, is drawn upwards by the torque arising from the weight ofthe overhanging patient. A bolt 73 connecting the end plate 70 to theadjusting mechanism or the couch 71 is thus constantly loaded with alateral force. The bolt 73 is preferably constructed with an undercut(not visible in FIG. 9), such that it cannot be withdrawn when it isloaded with a force. A second bolt 74 is guided through the plate 74connected to the transport means for the bed, into an elongated hole inthe end plate 70. As long as the bolt 73 is loaded, the bolt 74 is notloaded, and can therefore be changed without significant physical force.Position 1 shows the situation wherein the bed is connected to theadjusting mechanism (bolt 73 bearing the load).

If the transport system is then moved up to the bed, then moving thetable up moves the bed and the adjusting device upwards, and thereforethe plates 70 and 71, until the bolt 74 meets at the lower end of theelongated hole, and from then on absorbs the flow of force. If the tableis moved a further few millimetres upwards, then the bolt 73 iscompletely released from the load and may be withdrawn by hand. The bedis detached via the latching mechanism in the reverse of this sequence.

1. A patient positioning device for treatment planning and/or carryingout radiation treatment, comprising a patient bed on which a patient canlay, and an adjusting device that supports the patient bed forrotational movement about two axes; wherein the adjusting device isarranged between the patient bed and a supporting device beneath thepatient bed; wherein the adjusting device includes a base plate and acover plate that are movably linked together via a three-point orfour-point bearing; and wherein the adjusting device includes a guideslot and follower guided in the slot to provide two translatory and tworotatory degrees of freedom with respect to one another while preventingthe patient bed from shifting laterally with respect to the supportingdevice.
 2. The device as set forth in claim 1, comprising a positiontracking system that can detect both the positions of markings arrangedon a patient supported on the patient bed.
 3. The device as set forth inclaim 1, comprising one or more of the following immobilisation meansfor immobilising the patient on the patient bed: vacuum foils withcorresponding vacuum pumps elastic bands or foils stretched over thepatient vacuum cushions specially fitted to the patient's formthermoplastic body masks specially fitted to the patient's form formcushions or form blocks fitted to the patient's form.
 4. The device asset forth in claim 1, wherein axes are orthogonal and respectivelyextend longitudinally and laterally with respect to the patient bed. 5.The device as set forth in claim 1, wherein the adjusting deviceincludes at least two supports that are height adjustable pneumatically,hydraulically, piezoelectrically or electromechanically.
 6. The deviceas set forth in claim 5, wherein the patient bed is caused to rotateabout its longitudinal axis by counter-adjusting the two supports in theopposite directions.
 7. The device as set forth in claim 5, the patientbed is caused to rotate about its lateral axis by adjusting one or twohead-end or foot-end supports.
 8. The device as set forth in claim 5,the patient bed is caused to rotate about its lateral axis by adjustingat least one head-end and at least one foot-end support.
 9. The deviceas set forth in claim 5, comprising an adjustment controller that causesthe bed to rotate about its lateral axis by purposefully setting theadjusting speed of at least one head-end and at least one foot-endsupport, whereby the position of the apparent axis of rotation may beplaced in a desired position.
 10. The device as set forth in claim 5,comprising an adjustment controller that causes the bed to rotate aboutits longitudinal axis by purposefully setting the adjusting speed of atleast two supports, whereby the position of the apparent axis ofrotation can be placed in a desired position.
 11. The device as setforth in claim 1, wherein the adjusting device comprises a front,head-end support and a rear, foot-end support connected between the baseand cover plates, and wherein at least one of the supports isconstructed as a ball joint or as a universal joint.
 12. The device asset forth in claim 11, wherein at least one of the supports comprises atoggle lever with ball joints on both sides.